1
Seat No.: Enrolment
GUJARAT TECHNOLOGICAL UNIVERSITY
PDDC SEMESTER- VI • EXAMINATION SUMMER-2017
Subject Code: X60903 Date: 04/05/2017
Subject Name: High Voltage Engineering
Time: 10.30AM to 01:00PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
Q.1

Explain ionization by collision, photo ionization and positive ion impact in gaseous insulating material.
07

Explain basic Townsend's criteria for break-down in gaseous insulating medium. Derive expression for current growth in Townsend's criteria with consideration of primary and secondary ionization process.
07
Q.2

How electronegative gas is important in high voltage applications? Explain in detail with advantages.
07

List the different type of Break down mechanism for the solid dielectric. Explain the Electro-mechanical breakdown in solid and prove that thickness of the solid insulating material cannot be reducing more than 40
07
OR

Explain how α and Υ can be determine with experimental set-up.
07
Q.3

Discuss the different types of breakdown mechanism for liquid insulating material. Explain cavitations and bubble theory in detail.
07

Explain good properties of insulating materials
07
OR
Q.3

Explain cascaded transformer with a neat diagram.
07

Explain C.V.T with phasor diagram.
07
Q.4

Explain impulse testing of transformers.
07

Discuss Marx circuit for multistage impulse generator.
07
OR
Q.4

Explain how sphere gap can be used to measure peak value of voltages. What are the precautions needed to be taken.
07

Explain Electrostatic Voltmeters with neat diagram.
07
Q.5

What are the methods for measurement of High AC voltage measurement? Explain any one in detail.
07

Write a short note on capacitance potential dividers.
07
OR
Q.5

Explain High voltage test on insulator
07

Explain High voltage Schering bridge
07